JP4885977B2 - Process water reclamation system and method - Google Patents

Abstract

An arrangement for producing paper from e.g. old paper, comprises a treatment unit (100) connected to a paper machine (200). The treatment unit has one or more stages supplied with process water. Each process water treatment unit has a cleansing and/or material recovery unit, and at least one treatment unit has an anaerobic reactor with micro-organisms, as well as a scale elimination unit. At least one of the treatment units has a particle separation section for eliminating colloidal, colloidaly dissolved and particulate material, as well as a desalination unit. The scale elimination unit is in the form of a flotation plant.

Description

  The present invention relates to a process water treatment system, and more particularly to a process water treatment in the manufacture of paper. Here, the system comprises at least one process water treatment unit. Furthermore, the present invention relates to a process water treatment method, and more particularly to a process water treatment in paper manufacture.

  Treatment of process water is particularly needed in many technical fields where process water is guided in the circuit of the corresponding system in order to prevent concentration of process water containing interfering substances. This also applies in particular to process water in the manufacture of paper, and in fact applies to both the manufacture of paper from new fibers and in particular of paper from recycled paper.

  Paper has been increasingly produced from recycled paper over the past few decades. This is to reduce the consumption of energy in the production of paper and in particular to reduce the consumption of natural resources. About 2.2 metric tons of wood is required to produce 1 ton of primary fiber paper, but depending on the ratio of secondary fibers resulting from recycled paper to the total fiber content in recycled paper, paper recycling The required wood can be drastically reduced to zero. Furthermore, half energy and 1/3 new water is required for the production of recycled paper compared to making paper from primary fibers. However, at present, the quality of recycled paper is as high as that of primary fiber paper in terms of ink resistance, print, degree of whiteness, and resistance to deterioration.

  In the production of paper from recycled paper, the recycled paper is first mixed with water and crushed in a pulper or pulp production engine, and stirred and mixed to dissolve individual fiber compositions. This is followed by a fiber wash to remove non-fiber foreign matter from the pulp fiber. The fibers are then optionally bleached after optionally adding a small amount of primary fibers and finally processed into paper on a paper making machine. Accordingly, the corresponding system comprises an apparatus for processing recycled paper and a paper making machine. The recycled paper processing apparatus includes a recycled paper pulp manufacturing unit, that is, a pulper, a separation device for removing impurities, and a decker unit for removing process water. Here, in the recycled paper pulp manufacturing unit, the process water is supplied to the recycled paper so as to produce fiber pulp and finely break the fiber. It is also known to improve the quality of fibers processed from recycled paper by providing two or more recycled paper processing units or stages, or so-called loops, in the system. Here, each loop of the recycled paper processing apparatus and the paper making machine preferably include a dedicated process water treatment unit. Here, the individual water treatment units can be separated from each other by a decker unit provided between the individual loops.

  In order to be able to guide process water through all the loops in the circuit and thereby minimize the addition of new water, process water must be purified to the extent required by the individual process water treatment units. I must. For this purpose, the process water treatment unit always comprises a material regeneration unit and / or a material removal unit. Here, the fibers contained in the process water are mechanically removed from the process water and guided back to the recycled paper processing apparatus completely or partially. These material regeneration units or material removal units are always designed as sorting systems and / or pressure relief flotation separation (bubble separation) systems.

  A system for producing paper from recycled paper is known from DE 40422224 A1, which system comprises a recycled paper processing device with a loop and a paper making machine. The recycled paper processing apparatus includes a pulper, a separation device, a concentration unit that removes process water from the suspended pulp as much as possible, and a process water treatment unit that purifies the process water. Here, in the pulper, the recycled paper is guided to the pulper and mixed with the process water, whereby the wastepaper is made into a pulp again. The separation device is provided downstream of the pulper, and the impurities are separated from the suspended pulp produced in the pulper in the device. Next, the process water treatment unit includes a pre-purification device, an anaerobic purification stage, and an aerobic purification stage. Here, the anaerobic purification stage includes, for example, UASB. The process water purified in the process water treatment unit is discharged as waste water or, as in other embodiments, a part of the process water is guided back to the pulper as part of the repulp production water. Is guided back to the paper making machine. In this case, the partial flow of white water from the paper making machine is added to the process water guided through the process water treatment unit of the recycled paper processing apparatus.

The process water circuits of the paper making machine and the process water treatment unit are not completely separated from each other in this system, and for this reason, the quality of process water in the paper making machine and the quality of process water in the recycled paper processing equipment. Cannot be controlled efficiently and independently of each other. Another drawback of the previous embodiment is that the process water has a high hardness due to partial guidance in the circuit, and this high hardness hinders the operation of the anaerobic UASB reactor. Microorganisms are used in anaerobic reactors, and the function of these microorganisms is to bring the microorganisms to the top of the reactor so as to separate the biogas formed in the gas separator when decomposing organic compounds from process water. It is important to have a certain specific weight that can be raised. Here, the biogas is formed in the decomposition process and adheres to the microbial pellets. After separation of the biogas, this particular weight will not be particularly large and the microbial pellet will fall to the bottom of the reactor as the microorganisms are no longer involved in the purification process. However, depending on the structure and size of the microorganism, the microorganism acts as a nucleus of crystals for precipitating lime, which causes the lime to precipitate on the microorganism pellet at a certain hardness and at a corresponding pH value. The pellet cannot inherit its function because the precipitate changes the specific weight of the pellet innumerably. Also, the metabolic action of anaerobic microorganisms causes a change in the lime / carbon dioxide balance due to the formation of bicarbonate (HCO ₃ ⁻ ) among other substances, thereby reducing the precipitation of lime on microbial pellets. Further promote. Despite the precipitation of lime on the pellets, the recirculation amount in the anaerobic reactor was suspended in the reactor despite the greater specific weight of microorganisms to ensure the function of the fine pellet Must be increased to maintain pellets. However, the amount of recycle is limited to the need to maintain the hydrodynamic capacity of the separator and the laminar flow of the reactor. As the recirculation volume increases, carbon dioxide leaks, which causes the lime / carbon dioxide balance to precipitate lime due to increased pressure gradients on the negative and positive pressure sides of the pump in the recirculation line. It depends on.

  Accordingly, it is an object of the present invention to provide a system for treating process water and a corresponding method. Here, the process water is efficiently purified, and in particular, the hardness and quality of the process water is directly controlled. This system is also particularly suitable for the treatment of process water with high hardness such as process water in a system for producing paper from recycled paper. The treated water should be particularly purified to ensure that interference with the aerobic reactor due to lime precipitation is prevented.

  The object of the invention is satisfied by the system of claim 1, in particular by a system comprising at least one process water treatment unit. Here, at least one process water treatment unit includes an anaerobic reaction device and an lime removal unit in which anaerobic microorganisms are mixed.

  Since at least one process water treatment unit is equipped with an anaerobic reaction apparatus in which anaerobic microorganisms are mixed, impurities contained in process water, particularly organic and biological impurities, can be efficiently removed. The By such purification, the process water is completely or at least almost completely guided in the circulation path without causing concentration of impurities by being guided in the circulation path. This minimizes the new water required for the present invention. Since the process water treatment unit includes a lime removal unit in addition to the anaerobic reaction device, the hardness of the process water guided in the circulation path is lime that disturbs microorganisms contained in the anaerobic reaction device. Is controlled to not precipitate in the anaerobic reactor. This optimizes the efficiency of the anaerobic reactor. Overall, the system of the present invention guides process water at least nearly completely within the circuit and allows efficient control of process water quality. Another advantage of the system of the present invention is that anaerobically treated process water cannot survive or a significant number live in, for example, an aerobic environment where it exists in a treatment stage and water treatment container. Can be understood by the fact that the growth of microorganisms in corresponding parts of the system is reliably prevented, such as occurs in systems with reactors containing aerobic microorganisms, which are filled with anaerobic microorganisms .

  The process water treatment system of the present invention may generally be integrated into a system in which process water is guided in the circulation path. In particular, in the manufacture of paper, process water is contaminated with a substantial amount of impurities. For this reason, the system of the present invention is particularly suitable for the purification of process water generated in the production of paper. Here, process water is irrelevant whether it originates from a system that produces paper from new fibers or from a system that produces paper from recycled paper.

  In this case, the system of the invention comprises at least one material preparation device and / or at least one paper making machine in addition to at least one process water treatment unit. Here, the at least one process water treatment unit comprises an anaerobic reactor and an lime removal unit into which anaerobic microorganisms are mixed, which comprise at least one material preparation device and / or at least one paper making machine. It corresponds to.

  In particular, when the system of the present invention is a system for producing paper from recycled paper, the system can be used as a material preparation device for producing fiber material from recycled paper and / or a paper making machine for producing paper from pulp. A processing device is provided. Here, the recycled paper apparatus includes one or more stages, and the at least one stage and / or the paper making machine includes a dedicated process water treatment unit. Here, at least one process water treatment unit includes an anaerobic reaction device and an lime removal unit in which anaerobic microorganisms are mixed. In particular, if the paper making machine and all stages or loops of recycled paper processing equipment have a process water treatment unit with an anaerobic reactor and a lime removal unit, they are included in the quality of process water, ie process water. The amount of impurities is controlled individually in each loop. This enables optimal water quality management when producing paper from recycled paper.

  In order to efficiently use the recycled paper used in the system and the fibers contained in the system, providing at least one process water treatment unit with a material recycling unit and / or a material removal unit implements the present invention. It has been proposed in the best mode. Especially when the material regeneration unit or material removal unit is formed as a combination of a series material regeneration device (eg device with a screen barrier) and a fine flotation separation device (ie pressure relief flotation separation device) like a cascade Good results are obtained. Preferably, useful fibers are regenerated in the first stage formed as spray floating separation, and fine material is removed from the process water in the second stage, which is the material removal section.

  In another preferred embodiment, the at least one process water treatment unit further comprises a filtration unit for separating solid particles contained in the process water. This filtration unit is preferably arranged downstream of the lime removal unit and the anaerobic reactor.

  The lime removal unit is generally located upstream or downstream of the anaerobic reactor in the at least one process water treatment unit. It is advantageous to place a lime removal device downstream of the anaerobic reactor because the mass transport, ie the solids concentration in the process water, is lower than upstream of the anaerobic reactor. This is particularly advantageous in a paper manufacturing system where graph paper is manufactured. In contrast, placing the lime removal device upstream of the anaerobic reactor is particularly advantageous in corresponding systems where many fibers are contained in the process water and the fibers are returned after separation of the material. In a preferred embodiment, the at least one process water treatment unit comprises a material regeneration unit formed as a fine flotation separator or pressure relief flotation separator and / or a material removal unit. It is preferable that a lime removal unit is a process part of the anaerobic reaction apparatus arrange | positioned at the at least 1 process water treatment unit. This is because the lime removal unit is connected to one device with a fine levitation separator or a pressure levitation separator.

  If the lime removal unit of at least one process water treatment unit is a pressure relief flotation separator, very good results are obtained especially when impurities are removed from the process water. In pressure relief flotation separation, the process water to be treated is preferably first adjusted to a neutral or alkaline pH suitable for lime formation with an additional pH adjuster, for example, an alkaline solution of sodium. At this time, the pH is preferably 7 to 10, particularly preferably 7 to 9, and still more preferably 7.5 to 8.5. Optionally, a precipitating agent and / or an agglomerating aid may be mixed in the process water to promote lime formation. A pressure gas, preferably compressed air, is then added to the mixture thus produced, which is pressurized and then expanded or depressurized in a pressure relief flotation reactor so that it is added in advance. The pressurized gas is bubbled from water at least most as gas bubbles and flows upward. Here, the gas bubbles carry a lime flocculent precipitate contained in the process water, which is separated from the water.

  In order to efficiently separate lime, the pressure difference between pressurization and expansion is at least 2 bar, preferably at least 3 bar, particularly preferably at least 4 bar, more particularly preferably at least 5 bar Forming a pressure relief flotation separator is proposed in the best mode for carrying out the invention. The greater the pressure difference, the smaller the gas bubbles that are generated during expansion, thereby increasing the face / volume ratio of the gas bubbles and thus separating more lime.

  The pressure-removal flotation separation device preferably includes a precipitation device and a lime separation device. In the precipitation device, the lime is precipitated in the process water by adding a material selected from the group of pH adjusters, precipitants, coagulant aids and desirable combinations thereof. In the lime separator, precipitated lime is separated from process water. For example, the precipitation device is equipped with a pH adjusting device and a feed line for the precipitation agent and / or coagulant aid, and the lime separation device is a mixing unit for pressure gas, for a physical pressure gas solution in process water It is preferable to provide a gas solution reaction apparatus and a pressure release flotation separation reaction apparatus.

  Alternatively, instead of the previous embodiment, lime removal may be carried out after the corresponding precipitation, for example by means of centrifugal force using a centrifuge or cyclone.

  In order to achieve a homogeneous mixture of process water and the aforementioned materials selected from the group of pH adjusters, precipitants, flocculating aids and desirable combinations thereof, the system of the present invention comprises at least one of the foregoing. It is preferable to provide a mixing unit for a uniform mixture of two substances.

  In the foregoing embodiment, both the precipitation device and the lime separation device may be located downstream of the anaerobic reactor. However, it is equally possible to install a precipitator and a lime separator upstream of the anaerobic reactor, or to install a precipitator downstream of the anaerobic reactor and upstream of the anaerobic reactor. It is. In the case described above, the partial flow line leads from the anaerobic reactor to the precipitation device, and the process water leaving the precipitation device is guided to the lime separation device via the corresponding line. Here, the bypass line bypasses the precipitation device from the anaerobic reactor and leads to the filtration unit. The foregoing embodiments are particularly advantageous in systems that produce tissue paper that does not contain ash. In the two embodiments described above, at least the lime separator is located upstream of the anaerobic reactor. This lime separation device, preferably formed as a pressure relief flotation separator, may be integrated into a material regeneration unit and / or material removal unit, preferably formed as a fine flotation separation device.

  All types of anaerobic reactors known to those skilled in the art are used as anaerobic reactors in which anaerobic microorganisms are mixed. Here, the reactor is, for example, a contact sludge reactor, a UASB reactor, an EGSB reactor, a fixed bed reactor, or a fluidized bed reactor. Here, particularly good results are obtained when a UASB reactor and an EGSB reactor are used. A pre-oxidation reactor may be connected in front of the anaerobic reactor, whereby process water is supplied to the anaerobic reactor after acid generation and / or hydrolysis in the pre-oxidation reactor. Is done. Polymers such as polysaccharides, polypeptides and fats are broken down into monomers such as sugars, amino acids and fatty acids during hydrolysis of the enzyme by extracellular enzymes originating from the microorganisms, and these monomers are acidified by acidogenic microorganisms. During production, it changes to organic acids, alcohols, aldehydes, hydrogen and carbon dioxide.

  In the present invention, the material preparation device of the system comprises one or more stages, and good results are obtained especially in the case of 1 to 3 material preparation stages. Here, the individual stages are preferably separated from each other by a decker stage. The material preparation device preferably comprises two separate stages. In a system for producing paper from recycled paper, where the material preparation device is designed as a recycled paper processing device, one or more material preparation stages are formed as recycled paper processing stages.

  Regardless of the number of stages of the material preparation device, in another preferred embodiment of the present invention, in the paper processing system, both the at least one stage of the material preparation device and the paper making machine are dedicated process water treatment units. Is provided. Here, each process water treatment unit includes an anaerobic reaction device and a lime removal unit.

  In the best mode for carrying out the invention, it is proposed that all the stages of the material preparation apparatus and the paper making machine each have a dedicated process water treatment unit. Here, each process water treatment unit includes an anaerobic reaction device and a lime removal unit. All stages or loops of the manufacturing machine and material preparation equipment are equipped with an anaerobic reactor and a process water treatment unit with a lime removal unit so that the quality of process water, i.e. the amount of impurities contained in the process water, is in each loop. Are controlled individually. This allows optimal water quality management in paper production.

  More preferably, the system of the present invention comprises a waste water purification device. A portion of the process water guided into the circulation path is purified and discharged from the system via the purification device, and the discharged portion is replaced with fresh water.

  Here, the waste water purification device may comprise one or more devices selected from the group consisting of a material removal unit, a cooling unit, a biological waste water treatment unit, and a desirable combination thereof.

  In the embodiment described above, a partial flow line is preferably provided in the system leading from the waste water purification device back to the material preparation device and / or the paper making machine. Another subject of the invention is a method for the treatment of process water, in particular for the treatment of process water in the manufacture of paper, which method comprises at least one process water treatment step. At least a part of the process water supplied continuously to the process water treatment step is subjected to a purification step and a lime removal step in an anaerobic reaction apparatus in which anaerobic microorganisms are mixed.

  The process water continuously supplied to the process water treatment step preferably originates from a material preparation device, such as a recycled paper treatment device and / or a paper making machine.

  It has been proposed in the best mode for carrying out the invention that process water undergoes a pressure relief flotation separation step of a lime removal step.

  In the above embodiment, the pressure difference between pressurization and expansion in the pressure relief flotation separation step is at least 2 bar, particularly preferably at least 3 bar, more particularly preferably at least 4 bar, most preferably at least 5 bar. It is desirable to be.

  The inventive method is preferably implemented in the inventive system described above.

  The invention will be briefly described below by way of illustrating advantageous embodiments.

  The system shown in FIG. 1 includes a recycled paper processing device 100, and a paper manufacturing machine 200 that is disposed downstream of the recycled paper processing device and connected to the recycled paper processing device 100. Here, the recycled paper processing apparatus 100 includes two stages or loops 101a and 101b which are substantially separated from each other, which are indicated by a dashed-dotted line in FIG.

  The first stage 101a of the recycled paper processing apparatus 100 includes a material inlet 102, a pulper or pulp production engine 105, a separation device 110a, and a decker unit 115a, which are arranged in series and connected to each other. ing. In the present invention, the pulper or pulp production engine 105 is not to be understood only as a device comprising a device part as schematically shown in FIG. 1, in particular a combination of devices comprising a plurality of individual device parts, And should be understood as a combination of equipment with all of the components or units necessary for pulp production. The same applies to all of the separation device 110a, the decker unit 115a and other components shown in FIG.

  The pulp production engine 105 and the separation device 110a are connected to the waste treatment unit 118a via lines.

  The first stage 101a of the recycled paper processing apparatus 100 further includes a process water treatment unit 116a, and the process water generated in the system portion passes through this treatment unit, and is sent to a waste treatment unit 118a and a separation apparatus 110a. And is supplied from the decker unit 115a through a corresponding line. Here, the separation device 110a may be a serial separation device (not shown). The process water treatment unit 116a includes a material regeneration unit 120a, an anaerobic reaction device 125a in which anaerobic microorganisms are mixed, a lime removal unit 130a, and a filtration unit 140a, which are arranged in series and connected to each other. ing. The return line 145a communicates from the filtration unit 140a to the pulp production engine 105. In addition to or instead of the material recycling unit 120a, a material removal unit (not shown) may be provided in the recycled paper processing apparatus 100.

  Unlike the first stage 101a, the second stage 101b of the recycled paper processing apparatus 100 includes a separation device 110b, an oxidation-reduction unit 112, and a decker unit 115b connected to the decker unit 115a, which are arranged in series. And connected to each other. Further, the second stage 101b includes a process water treatment unit 116b formed in the same manner as the process water treatment unit 116a of the first stage 101a. The filtration unit 140b in the second stage 101b of the recycled paper processing device 100 is connected to the separation device 110b via a return line 145b, and is connected to the separation paper 110a via a partial flow line 170a extending from the filtration unit 140a. Connected to the return line 145a in the first stage 101a. The separation device 110b and the oxidation-reduction unit 112 are connected to the waste treatment unit 118b via a corresponding line, and the decker unit 115b is directly connected to the material regeneration unit 120b of the process water treatment unit 116b. Furthermore, a line leads from the redox unit 112 to the material recycling unit 120b.

  The paper manufacturing machine 200 includes a centrifuge 202, a fine separation device 204, a paper manufacturing machine forming unit 206, a paper manufacturing machine pressing unit 208, and a drying unit 210, which are arranged in series and connected to each other. ing. The centrifuge 202 and the fine separation device 204 are connected to the waste treatment unit 212, and the paper maker forming unit 206 and the paper maker pressing unit 208 are connected to the fiber recycling unit 214. Further, the waste treatment unit 212 and the fiber regeneration unit 214 are connected to the process water treatment unit 216 via corresponding lines. The process water treatment unit 216 includes a material removal unit 220, an anaerobic reaction device 225 in which anaerobic microorganisms are mixed, a lime removal unit 230, and a filtration unit 240. Further, the return line 270 communicates from the filtration unit 240 of the paper making machine 200 to the line 170 in the second stage 101b of the recycled paper processing apparatus 100. The fiber regeneration unit 214 and the material removal unit 220 may be connected to, for example, an apparatus part formed as a fine floating separation.

  In addition, a new water line 280 is provided in the area of the paper making machine 200 and new water is supplied to the paper making machine through this line. Here, the new water supply line 280 opens to various positions of the paper making machine 200, for example, the supply line towards the centrifuge 202 and / or the paper making machine forming part 206 and / or the paper making machine pressing part 208. For this reason, the exact location of the new water supply line 280 is not shown in FIG. Furthermore, a waste water line 300 is provided in the system, and waste water is discharged from the system through this waste water line. Waste water line 300 may be located at various locations in the system, for example, line 170, and for this reason, the exact location of waste water line 300 is not shown in FIG. The waste water line 300 leads to a mechanical material removal unit 305, to which a cooling unit 310 and a biological waste water purification unit 315 are connected. The line leads from a biological wastewater purification unit 315 equipped with a lime removal unit and a filtration unit to the public water 400, for example a river, but a partial stream of this purification unit can be used in the paper making machine or pulp processing section if necessary. May be returned.

  When the system is in operation, the recycled paper is continuously guided to the pulp manufacturing engine 105 in the first stage 101 a of the recycled paper processing apparatus 100 through the material inlet 102. Here, the recycled paper is mixed with process water supplied via the return line 145a and pulverized to regenerate the fibers. The fibers regenerated in the pulp production engine 105 are continuously guided to the separation device 110a as fiber suspensions, and the process water generated in the pulp production engine 105 and containing fiber residues is treated as a waste treatment unit 118a. First guided to. From here, this process water is guided to the material recycling unit 120a in the process water treatment unit 116a of the recycled paper processing apparatus 100 after the waste is separated. In the separation device 110a, lighter or heavier foreign objects larger than the fiber, such as coarse impurities in the form of plastic foil and plastic pieces, are separated from the fiber suspension. At this time, this separation is generally performed in a plurality of stages by, for example, a screen barrier. In addition, floating separation occurs in the separation device to remove pigment, ink and dye particles (deinking). Furthermore, fine material and ash are separated by material cleaning. The suspended fiber is condensed by the process water treatment in the decker unit 115a. Here, the decker unit 115a is disposed downstream of the separation device 110a and is preferably formed as a decker filter and / or a screw press, and the fiber suspension is recycled paper processing apparatus as a condensed fiber suspension. Move from the 100 decker units 115a to the separation device 110b of the second stage 101b. One partial stream of process water generated in the separation apparatus 110a is guided to the waste treatment unit 118a, and the other partial stream of process water generated in the separation apparatus 110a is a decker unit 115a of the first stage 101a. In addition to the process water generated in step 1, the water is directly guided to the material recycling unit 120a of the process water treatment unit 116a in the first stage 101a of the recycled paper processing apparatus 100 through a corresponding line. Here, the pulp is separated from the process water contained in the regeneration unit, and the separated process water is supplied again to the treatment process. The material regeneration unit 120a is preferably designed as a pressure relief flotation separator.

  Alternatively, a partial stream of process water removed from the decker unit 115a or all process water removed from the decker unit 115a may be returned directly to the pulp making engine 105, ie bypassing the process water treatment unit 116a. Good. In particular, in the manufacture of paper, such as the manufacture of graph paper, where the solids concentration of process water is low, the material recycling units 120a, 120b or the material removal units 122, 220 may be omitted.

  In the system shown in FIG. 1, the process water generated in the waste treatment unit 118a is guided to the material recycling unit 120a. However, instead of this, the process water generated in the waste treatment unit 118a can be discharged from the recycled paper processing apparatus 101a as waste water. For example, process water may be guided through the waste water line 300 to the mechanical material removal unit 305 and continuously passed to the cooling unit 310 and the biological purification unit 315.

  The process water separated from the pulp is continuously guided from the material regeneration unit 120a to the anaerobic reactor 125a in which anaerobic microorganisms are mixed. In this reactor, chemical and biological impurities are decomposed by the effects of anaerobic microorganisms in the process water. Here, a cooling stage (not shown) and a pre-acidification reactor (not shown) in which the process water is acid-generated and / or hydrolyzed is anaerobic in order to adjust the process water to the optimum temperature range. It may be connected before the sex reaction device 125a. The process water thus separated from chemical and biological impurities is guided from the anaerobic reactor 125a to the lime removal unit 130a. Here, this removal unit is arranged downstream and is preferably designed as a pressure relief flotation separator. In the lime removal unit 130a, most of the carbonate and hydrogen carbonate present in the process water precipitate as lime and are removed from the process water. In addition, so-called “flash oxidation” occurs in the lime removal unit 130a. In this removal unit, the end product of microorganisms formed in the anaerobic reactor 125a is oxidized by the supplied molten air or air saturation, thereby decomposing and / or stepping through the additional oxidation of impurities. Stirring of the material contained in the irrigation water occurs and odor emission is greatly reduced. Here, lime precipitation occurs by changing the lime / carbon dioxide balance. This lime precipitation is achieved by adjusting with optimum chemicals, in particular pH adjusting agents. The pH of the process water is adjusted to a neutral or alkaline value, preferably a value of 7 to 10, particularly preferably a value of 7 to 9, more particularly preferably a value of 7.5 to 8.5, by means of a regulator. The In addition, for this purpose, precipitants and / or flocculating aids may be added to the process water, thereby producing a lime flocculent precipitate of a size suitable for lime precipitation and effective separation. To make it easier. Furthermore, a pressure gas, for example compressed air, is guided to the pressure relief flotation separator, and the mixture thus produced is pressurized and then depressurized. This causes the pressure gas to bubble from the mixture and flow into the top of the device as small bubbles. Thereby, solids, in particular lime flocs, are carried and separated from the process water. The process water purified by removing lime in this way is supplied from the lime removing device 130a to the filtration unit 140a. Here, the filtration unit 140a is formed as, for example, a sand filtration unit for removing a specific material remaining from the process water. Furthermore, a desalting apparatus (not shown) may be connected after the filtration unit 140a.

  The process water that has been purified by the process water treatment unit 116a in the first stage 101a of the recycled paper processing apparatus 100 and from which lime has been removed is returned to the pulper or pulp production engine 105 via the return line 145a.

  The condensed fiber suspended matter discharged from the decker unit 115a in the first stage 101a of the recycled paper processing apparatus 100 moves to the separation stage 110b, and from here to the oxidation-reduction unit 112, and then from the fiber suspended matter as much as possible. It is condensed by the decker unit 115b of the second stage 101b so as to remove the process water. Similar to the first stage 101a of the recycled paper processing apparatus 100, one partial flow of process water generated in the separation apparatus 110b and process water generated in the oxidation-reduction unit 112 is guided to the waste treatment unit 118b, and here The process water generated from is guided to the material recycling unit 120b. The other partial flow of process water generated in the oxidation-reduction unit 112 and the process water generated in the decker unit 115b are directly guided to the material recycling unit 120b of the process water treatment unit 116b in the second stage 101b of the recycled paper processing apparatus 100. At the same time, the water is purified in the process water treatment unit 116b and lime is removed. The process water thus treated is returned from the filtration unit 140b to the separation device via the line 170 and the return line 145b. The surplus of process water is guided to the first stage 101a of the recycled paper processing apparatus 100 via the partial flow line 170a and to the pulp manufacturing engine 105 via the return line 145a.

  In the paper manufacturing machine 200, the condensed pulp suspended matter continuously supplied from the decker unit 115b is separated into a centrifuge 202, a fine separation device 204, a paper manufacturing machine forming unit 206, a paper manufacturing machine pressing unit 208, and a drying unit. It is processed into paper by means of 210. Here, the centrifuge 202 separates a specific weight portion heavier or lighter than water. Process water generated in the system parts 202, 204 is guided to the waste treatment unit 212, and process water generated in the system parts 206, 208 is guided to the fiber regeneration unit 214. Wastes are stacked in the waste treatment unit 212, and the process water generated from the paper making machine forming unit 206 and the paper making machine press unit 208 is separated in advance in the fiber recycling unit 214 and the fibers Is separated from the process water. The process water generated in the waste treatment unit 212 and the fiber recycling unit 214 is continuously guided to the process water treatment unit 216 of the paper making machine 200, and the material removal unit 220, the anaerobic reaction device 225, and the lime removal unit. 230 and filtration unit 240 continuously flow. Here, these function like portions of the corresponding system described above in the process water treatment units 116 a and 116 b of the recycled paper treatment apparatus 100. Instead, the process water generated in the waste treatment unit 212 is discharged from the system as waste water, and only the process water generated in the fiber regeneration unit 214 passes through the process water treatment unit 216 of the paper making machine 200. May be continuously guided. Process water that has been removed from the filtration unit 240 and purified to remove lime is guided largely back to the centrifuge 202 of the paper making machine 200 via the return line 270 and the partial flow line 270b. At the same time, surplus process water is guided to a line 170 extending from the filtration unit 140b in the second stage 101b of the recycled paper processing apparatus 100 via the partial flow line 270a.

  A completely closed process water circuit is generally possible, but concentration may result from long-term agitation of the material, which can severely compromise the efficiency of the system. A relatively small amount of new water compared to the amount of process water guided into the circulation path is supplied to the process, in particular to the paper making machine 200, via a new water line 280. Corresponding amounts of process water are removed from the process via the waste water line 300 and purified via the material removal unit 305, the cooling unit 310 and the biological waste water purification unit 315, after which the stream is discharged into the waste water. To the public water 400. Here, the biological wastewater purification unit 315 may include a lime removal unit and / or a filtration unit. Further, as described above, the process water optionally discharged from the waste treatment units 118a, 118b, and 212 is removed from the process through the waste water line 300, and the material removal unit 305, the cooling unit 310, and the biological body are removed. It may be purified through a biological wastewater purification unit 315.

  The configuration of the lime removal units 130a, 130b, and 230 shown in FIG. 1 is particularly preferable for producing graph paper. This is due to the relatively low solids concentration in mass transport or process water.

  The embodiment shown in FIG. 1 is a system for producing paper from recycled paper. Here, the pulp production engine 105, separation devices 110a and 110b, decker units 115a and 115b, redox unit 112, centrifuge 202, fine separation device 204, paper making machine forming unit 206, and paper making machine shown in FIG. The press section 208 is shown schematically but does not reproduce the details of the paper manufacturing system. For example, one or both of the two separation devices 110a and 110b may be formed of a plurality of stages and continuously include a plurality of separation devices.

  The system of the present invention may be a system for producing paper from new fibers or other desired system. In another desired system, at least one process water treatment unit is provided, the at least one process water treatment unit comprising an anaerobic reactor mixed with anaerobic microorganisms and a lime removal unit. In the above-described case, the pulp production engine 105, separation devices 110a and 110b, decker units 115a and 115b, redox unit 112, centrifuge 202, fine separation device 204, paper making machine forming unit 206, and paper shown in FIG. The manufacturing machine press section 208 is replaced with another corresponding apparatus or apparatus section.

  In FIG. 1, the system comprises a pulp processing unit consisting of two stages. In particular, it is naturally possible to provide two or more material preparation stages in parallel in order to produce a paper consisting of a plurality of layers.

  FIG. 2 shows a schematic diagram of the stage 101a of the recycled paper processing apparatus, and the stage 101a includes a process water treatment unit 116a according to the second embodiment of the present invention. Here, the stage 101a is replaced with a corresponding process water treatment unit 116a of the first stage 101a in the recycled paper processing apparatus 100 of the system shown in FIG. Alternatively, all of the process water treatment units 116a, 116b, and 216 of the system shown in FIG. 1 can be replaced with the process water treatment unit 116a shown in FIG.

  In contrast to the process water treatment unit 116a shown in FIG. 1, the stage 101a shown in FIG. 2 includes a material disposed between the material regeneration unit 120a and the anaerobic reactor 125a in addition to the material regeneration unit 120a. A removal unit 122 is provided. The return line 124 leads from the material regeneration unit 120 to the pulp production engine 105.

  Another difference from the embodiment shown in FIG. 1 is that the stage 101a shown in FIG. 2 does not include the waste treatment unit 118a. However, instead of this, a waste treatment unit (not shown) may be provided in the embodiment shown in FIG. The process water generated in the pulp production engine 105 and the partial flow of process water generated in the separation device 110a are supplied through the processing unit via corresponding lines. Process water removed from the treatment unit is guided to the material regeneration unit 120a or removed from the system as waste water.

  Further, a precipitation device 135 is provided downstream of the anaerobic reaction device 125a in the process water treatment unit 116a and includes two supply lines 136 and 137. A pH adjusting agent such as an alkali solution of sodium, a precipitating agent such as polyaluminum chloride and / or an agglomerating aid such as polyacrylamide is supplied through these supply lines. The bypass line 139 bypasses the precipitation device 135 from the anaerobic reaction device 125 a to the filtration unit 140 a and guides the partial flow line 126 to the precipitation device 135. A partial flow return line 138 leads from the settling device 135 to the material removal unit 122.

  During operation of the stage 101 a shown in FIG. 2, process water continuously generated in the pulp production engine 105, the separator 110 a and the decker unit 115 a is guided to the material regeneration unit 120 a and from there to the material removal unit 122. Is done. Coarse fibers are maintained in the material regeneration unit 120a and guided through the return line 124 back to the pulp making engine. The process water generated in the material regeneration unit 120 a is guided to the material removal unit 122. Here, in the regeneration unit 120a, fine organic and / or inorganic specific materials are separated from the process water. Process water is continuously guided from the material removal unit 122 to the anaerobic reactor 125a. The main stream of at least 50% process water leaving the anaerobic reactor 125a is guided to the filtration unit 140a via the bypass line 139 and from there to the pulp making engine 105 via the return line 145a. The other partial stream consisting of less than 50% process water leaving the anaerobic reactor 125 a is guided to the lime precipitation unit 135 via the partial flow line 126. Here, a pH adjusting agent and a precipitating agent and / or a coagulant aid are supplied to the precipitator via supply lines 136 and 137, thereby precipitating lime in the process water. A partial stream of process water exiting the lime settling device 135 is guided through a partial flow return line 138 back to a material removal unit 122 designed as a fine levitation separation unit. Here, in the removal unit 122, the precipitated lime is separated from the process water.

  This embodiment is particularly suitable for producing tissue paper from recycled paper.

  In the embodiment shown in FIG. 2, a recycled paper treatment system has been described, but it should be understood that the process water treatment unit 116a shown in FIG. 2 is a system for producing paper from new fibers or at least one process water treatment. It may be provided in other desired systems with units.

  FIG. 3 shows a schematic view of the stage 101a of the recycled paper processing apparatus. The stage 101a includes a process water treatment unit 116a according to the third embodiment of the present invention. Here, the stage 101a is replaced with a corresponding process water treatment unit 116a of the first stage 101a in the recycled paper processing apparatus 100 of the system shown in FIG. Alternatively, all of the process water treatment units 116a, 116b, and 216 of the system shown in FIG. 1 can be replaced with the process water treatment unit 116a shown in FIG.

  In the process water treatment unit 116a shown in FIG. 3, the precipitation device 135 is provided upstream of the material regeneration unit 120a and includes two supply lines 136 and 137. A pH adjusting agent such as an alkali solution of sodium, a precipitating agent such as polyaluminum chloride and / or an agglomerating aid such as polyacrylamide is supplied to the precipitator 135 via these supply lines. Alternatively, the waste treatment unit (not shown) described in the embodiment shown in FIG. 1 may be provided in this embodiment.

  During the operation of the process water treatment unit 116a, the process water generated in the pulp production engine 105, the separation device 110a, and the decker unit 115a is continuously guided to the precipitation device 135. Here, in the precipitation apparatus 135, the carbonate and bicarbonate contained in the process water precipitate as lime in the process water. This precipitation occurs by adding a pH adjusting agent, a precipitating agent and / or an agglomerating aid to adjust the corresponding precipitation conditions. The mixture thus produced is guided to a material regeneration unit 120a designed as a pressure relief flotation separator. Here, in the reproduction | regeneration unit 120a, the fiber and the lime fluff-like deposit which were contained in process water are isolate | separated. The material regeneration unit 120a functions continuously and simultaneously as a lime separation unit.

  After being separated into lime and fiber, process water flows through the anaerobic reactor 125a and filtration unit 140a, and then through the return line 145a, the material regeneration units 120a, 120b and / or the material removal unit (FIG. Guided to return to (not shown).

  Accordingly, a lime removal unit that is advantageous for the system shown in FIG. 1 is combined with the pulp making engine 105 in the process water treatment unit 116a shown in FIG.

It is the schematic of the system which manufactures paper from the recycled paper in 1st Example of this invention. It is the schematic which shows the stage of the material preparation apparatus in 2nd Example of this invention. It is the schematic which shows the stage of the material preparation apparatus in the 3rd Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Material / recycled paper processing apparatus 101a ... 1st stage in material / recycled paper processing apparatus 101b ... 2nd stage in material / recycled paper processing apparatus 102 ... Material inlet 105 ... Pulpa / pulp production engine 110a ... separation device 110b ... separation device 112 ... oxidation unit / reduction unit 115a ... decker unit 115b ... decker unit 116a ... material / recycled paper processing device process Water treatment unit 116b: Water treatment unit for process of material / recycled paper processing device 118a ... Waste treatment unit 118b ... Waste treatment unit 120a ... Material recycling unit 120b ... Material recycling unit 122 ..Material removal unit 124 ... return line 125a ... anaerobic reaction 125b ... Anaerobic reaction device 126 ... Partial flow line 130a ... Lime removal unit 130b ... Lime removal unit 135 ... Lime precipitation device 136 ... Supply line for pH adjuster 137 ...・ Supply line for precipitant / aggregation aid 138... Partial flow return line 139... Bypass line 140a... Filtration unit 140b ... Filtration unit 145a ... Return line 145b ... Return line 170 ... Line 170a ... Partial flow line 200 ... Paper making machine 202 ... Centrifuge 204 ... Fine separation device 206 ... Paper making machine forming part 208 ... Paper making machine press part 210: Drying unit 212: Waste disposal unit 214: Fiber recycling unit 216: Paper manufacturing machine process Water treatment unit 220 ... Material removal unit 225 ... Anaerobic reactor 230 ... Lime removal unit 240 ... Filtration unit 270 ... Return line 270a ... Partial flow line 270b ... Partial flow Line 280 ... New water supply line 300 ... Waste water line 305 ... Mechanical material removal unit 310 ... Cooling unit 315 ... Biological waste water purification unit 400 ... Public water

Claims (24)

A process for treating process water guided in a circulation path in the manufacture of paper ,
In an anaerobic reaction apparatus (125a, 125b, 225) that includes at least one process water treatment step and at least a part of the process water continuously supplied to the process water treatment step is mixed with anaerobic microorganisms. While receiving the purification step and the lime removal step, the process water is subjected to the pressure removal flotation separation (bubble separation) step in the lime removal step, and in the pressure removal flotation separation step, the pH of the process water is first the method for process water treatment, characterized in Rukoto set to a pH of 7-10.   The method according to claim 1, characterized in that the process water continuously supplied to the process water treatment step originates from a material preparation device (100) and / or a paper making machine (200).   3. The process water continuously supplied to the process water treatment step comes from at least one stage of a recycled paper treatment device (100) and / or a paper making machine (200). the method of.   The pressure difference between pressurization and expansion in said pressure relief flotation separation step is at least 2 bar, preferably at least 3 bar, particularly preferably at least 4 bar, more particularly preferably at least 5 bar. Item 2. The method according to Item 1.   Implemented in a system comprising at least one process water treatment unit (116a, 116b, 216), wherein the at least one process water treatment unit (116a, 116b, 216) is anaerobically mixed with the anaerobic microorganisms. The method according to claim 1, comprising a sex reaction device (125 a, 125 b, 225) and a lime removal unit (130 a, 130 b, 230).   The system comprises at least one material preparation device (100) and / or at least one paper making machine (200), wherein the at least one process water treatment unit (116a, 116b, 216) is the at least one The anaerobic reaction device (125a, 125b, 225) and the lime removal unit (130a) mixed with the anaerobic microorganisms corresponding to one material preparation device (100) and / or the at least one paper making machine (200) , 130b, 230).   The system includes the recycled paper processing device (100) for producing pulp from the recycled paper and / or the paper making machine (200) for producing paper from the pulp as the material preparation device (100), The recycled paper processing apparatus (100) includes one or more stages (101a, 101b), and at least one of the stages (101a, 101b) and / or the paper making machine (200) is a dedicated process water treatment. The unit (116a, 116b, 216) includes the anaerobic reaction device (125a, 125b, 225) in which the at least one process water treatment unit (116a, 116b, 216) is mixed with the anaerobic microorganism. And the lime removal unit (130a, 130b, 230). The method according to 5 or 6.   The at least one process water treatment unit (116a, 116b, 216) further comprises a material regeneration unit (120a, 120b, 220) and / or a material removal unit (122). The method according to any one.   A filtration unit (at least one process water treatment unit (116a, 116b, 216)) disposed downstream of the lime removal unit (130a, 130b, 230) and the anaerobic reactor (125a, 125b, 225). 140a, 140b, 240). The method according to any of claims 5-8.   The lime removal unit (130a, 130b, 230) is located upstream of the anaerobic reactor (125a, 125b, 225) in the at least one process water treatment unit (116a, 116b, 216) of the system. 10. A method according to any one of claims 5-9.   The lime removal unit (130a, 130b, 230) is disposed downstream of the anaerobic reactor (125a, 125b, 225) in the at least one process water treatment unit (116a, 116b, 216) of the system. 10. A method according to any one of claims 5-9.   12. A method according to any of claims 5 to 11, characterized in that the lime removal unit (130a, 130b, 230) of the system is a pressure relief flotation separator.   The pressure relief flotation separator is formed so that the pressure difference between pressurization and expansion is at least 2 bar, preferably at least 3 bar, particularly preferably at least 4 bar, more particularly preferably at least 5 bar. The method according to claim 12, wherein:   The pressure relief flotation separation device comprises a precipitation device (135) and a lime separation device, wherein the precipitation device is a substance selected from the group comprising a pH adjuster, a precipitation agent, a coagulant aid and desirable combinations thereof. 14. The method according to claim 12, wherein lime is precipitated in the process water by adding, and the precipitated lime is separated from the process water in the lime separation device.   15. The system comprises a mixing unit for uniformly mixing a material selected from the group comprising a pH adjusting agent, a precipitating agent, a coagulant aid, and desirable combinations thereof into the process water. The method described in 1.   The method according to claim 14 or 15, characterized in that the precipitation device (135) and the lime separation device are respectively arranged downstream or upstream of the anaerobic reaction device (125a, 125b, 225).   The precipitation device (135) is disposed downstream of the anaerobic reaction device (125a, 125b, 225), and the lime separation device is disposed upstream of the anaerobic reaction device (125a, 125b, 225). And a partial flow line (126) leads from the anaerobic reactor (125a, 125b, 225) to the precipitation device (135), and the process water exiting the precipitation device (135) is line (138). Through the lime separator and the bypass line (139) bypasses the settling device (135) from the anaerobic reactor (125a, 125b, 225) to the filtration unit (140a). 16. A method according to claim 14 or 15, characterized in that   18. Method according to claim 17, characterized in that the lime separator is designed simultaneously as a material regeneration unit (120a, 120b, 220) and / or a material removal unit (122).   The material preparation unit (100) comprises 1-3 stages (101a, 101b), particularly preferably two stages (101a, 101b) separated from each other by a decker stage (115a). Item 19. The method according to any one of Items 5 to 18.   At least one of the stages (101a, 101b) and the paper making machine (200) of the material preparation device (100) includes dedicated process water treatment units (116a, 116b, 216), respectively. The processing unit (116a, 116b, 216) comprises the anaerobic reactor (125a, 125b, 225) and the lime removal unit (130a, 130b, 230), respectively. The method of crab.   All the stages (101a, 101b) and the paper making machine (200) of the material preparation device (100) are provided with dedicated process water treatment units (116a, 116b, 216), respectively, and the process water treatment unit 21. Method according to claims 5-20, characterized in that (116a, 116b, 216) comprises said anaerobic reactor (125a, 125b, 225) and said lime removal unit (130a, 130b, 230), respectively.   The said system is provided with the waste water purification apparatus, A part of said process water is purified through this waste water purification apparatus, and is discharged | emitted from the said system. The method of crab.   23. Method according to claim 22, characterized in that a partial flow line leads back from the waste water purification device to the material preparation device (100) and / or the paper making machine (200).   The wastewater device comprises one or more devices selected from the group comprising a material removal unit (305), a cooling unit (310), a biological wastewater treatment unit (315), and desirable combinations thereof. The method according to claim 22 or 23.

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